Plasma cell granuloma of the oral cavity: a report of two cases and review of the literature.

We report two rare cases of plasma cell granuloma arising in the extragingival oral cavity. These are tumorous proliferations composed predominantly of reactive plasma cells. Both patients presented with solitary mass lesions that were clinically suspicious for malignancy. One patient presented with a mass that grew slowly for 2 years and involved the lip; in the second patient, a mass developed in the buccal mucosa Histologically, both lesions were characterized by lobules of plasma cells separated by thick collagenous bands. A variable number of admixed lymphocytes and histiocytes was noted in both cases. In situ hybridization and immunostaining for kappa and lambda light chains revealed a polyclonal plasma cell population. In situ hybridization for Epstein-Barr virus failed to demonstrate evidence of viral expression in either case. Both patients are free of disease after 8-month and 12-month follow-ups. Although plasma cell granuloma in the oral cavity is rare, it is important to recognize this entity as a benign inflammatory lesion.